Are Grains Good for Dogs? The Science Behind Healthy Grains in Dog Food

By Caroline Buck, Co-founder of Petaluma

Most dog owners have absorbed a quiet rule about feeding: protein is good, and carbs are something to keep to a minimum. Grains sit right in the crosshairs of that rule, written off as filler or blamed for allergies. But are grains actually good for dogs, or something to steer around? This article looks at what healthy grains really bring to the bowl: plant protein, fiber, and a range of vitamins and minerals. It also covers why "net carbs" is the more useful number, how dogs evolved to digest starch, and what the grain-free heart-disease scare did and did not show.

Why healthy grains belong in a dog's bowl

Carbohydrates picked up a bad reputation from modern human diets, where the real problem is overconsumption of refined carbs like baked goods, sweets, and white bread. That worry got transferred onto dog food, even though carbohydrates are a valuable, efficient source of energy. The paleo and low-carb movements cast carbs as the enemy, and pet marketing followed with grain-free bags framed as the purer choice. That hype has since cooled, especially after grain-free diets drew heart-disease scrutiny, yet many pet parents are still unsure whether dogs need grains at all.

Grains are like any other ingredient. Quality runs along a spectrum: nutritional value, sourcing, and how the grain is worked into a recipe all vary. At Petaluma, we choose whole grains for what they contribute to your dog's long-term health, not to stretch a recipe or lower a cost. Review work finds whole grains supply meaningful protein, fiber, vitamins, and minerals to pet diets, alongside energy (de Godoy 2016).

Grains are more than carbohydrates

Whole grains are nutritional powerhouses, not shorthand for carbs. They carry the bran and germ, the layers that hold most of a grain's protein, fiber, vitamins, and minerals (de Godoy 2016). In a balanced diet, that gives them an important role well beyond energy.

What whole grains contribute

• Protein and amino acids: cereal grains supply plant protein that adds to a recipe's amino acid pool, complementing other ingredients.
• Fiber: whole grains bring both soluble and insoluble fiber, which feed gut bacteria and support steady digestion.
• B vitamins: grains contribute thiamine, niacin, riboflavin, and other B vitamins involved in turning food into energy.
• Minerals: whole grains are a source of manganese, magnesium, phosphorus, selenium, and zinc.

The fiber is worth its own note. Insoluble fiber adds bulk that supports regular, formed stools, while soluble fiber feeds beneficial gut bacteria. A whole grain does several jobs at once: it supplies energy while adding protein, fiber, and micronutrients. That makes it a real contributor to a balanced recipe, a fuller picture than the single word "carbs" suggests.

Why "net carbs" is the better metric

A macro profile of protein, fat, and carbs tells you surprisingly little about a food's real value. Two foods can post the same numbers and still nourish a dog very differently. Real value comes from how the ingredients work together to support a balanced diet, a healthy gut, and long-term wellness.

Carbohydrate is a clear example. Labels rarely list it, and the usual estimate rolls starch, sugars, and fiber into one figure. Those components behave very differently once a dog digests them.

A "net carb" view pulls the fiber out of that total. A food can look high in carbohydrate when much of the number is fiber that feeds the gut and steadies digestion, not starch. We break this down further in carbs in dog food: net carbs explained.

Dogs are built to digest starch

One argument against grains is that dogs are wolves at heart and cannot handle starch. The genetics tell a different story. As dogs were domesticated alongside farming people, they adapted to a starch-rich diet.

A landmark genome study found that dogs carry, on average, a sevenfold increase in copies of the AMY2B gene compared with wolves (Axelsson 2013). AMY2B codes for pancreatic amylase, the enzyme that starts breaking starch down into sugar. The same study found selection on MGAM and SGLT1, two more genes that help dogs convert and absorb the sugar from starch.

Dogs are equipped for cooked grains in a way their wild ancestors were not. We trace this shift in more depth in when dogs became omnivores.

The grain-free scare: what the science shows

Worry about grains has swung back and forth in recent years. First came the grain-free craze, which cast grains as filler or as a mismatch for a dog's "ancestral" diet. Then the worry flipped: people grew alarmed that grain-free diets might cause heart disease, after a widely publicized FDA investigation.

What the FDA investigation found

In 2018 the U.S. Food and Drug Administration began looking into reports of canine dilated cardiomyopathy, a disease of the heart muscle shortened to DCM. Many affected dogs were eating grain-free diets high in peas, lentils, and other legumes (FDA). The concern landed on the legumes that replaced grains, not on grains.

The investigation never established a cause. The FDA found that taurine deficiency did not appear to be the main driver, and in 2022 it said it would not issue further updates without stronger evidence.

Through both swings, veterinary nutrition experts have kept the same advice: balanced diets that include grains. We cover the legume side of this in our review of legumes in dog diets.

The allergy myth

Food allergies in dogs are less common than the marketing suggests. When they do occur, the most frequently reported triggers are animal proteins. A review of the evidence lists beef, dairy, chicken, and wheat as the top canine food allergens (Mueller 2016).

Wheat is the one grain on that list, and even it ranks below three animal proteins. Oats and barley, the grains Petaluma uses, are rarely named as allergens. A dog with a confirmed grain sensitivity should avoid the grain in question, and a veterinarian can guide that. Grains themselves are rarely the culprit.

The grains in Petaluma: oats and barley

Petaluma's baked recipes use two whole grains: organic oats and organic barley. Both were chosen for the same standout nutrient, a soluble fiber called beta-glucan. Beta-glucan sits in the cell walls of oats and barley in higher amounts than in most other cereals.

Beta-glucan forms a gel in the gut that slows digestion and feeds beneficial bacteria. In a controlled feeding trial, dogs given oat beta-glucan for 71 days showed lower total cholesterol and lower LDL and VLDL cholesterol than dogs on the control diet (Vasconcellos 2018). In people, this same fiber blunts the rise in blood sugar after a meal compared with refined grains (Tosh 2013). A slower, steadier release of energy is a sensible fit for everyday feeding.

Oats and barley at a glance

Grain	Standout nutrients	Fiber highlight	Why Petaluma uses it
Organic oats	Plant protein, manganese, phosphorus, thiamine	High in soluble beta-glucan	Gentle, cholesterol-supporting fiber; steady energy
Organic barley	Plant protein, selenium, manganese, magnesium	High in soluble beta-glucan; among the lower-glycemic grains	Slow-release carbohydrate and mineral density

Both recipes are formulated by veterinary nutritionists and tested for AAFCO compliance, with a published nutritional profile on each product page. The grains are part of a whole-food approach, not a filler line at the bottom of the label.

Frequently asked questions

Are grains bad for dogs?

No. Whole grains are a healthy source of protein, fiber, B vitamins, and minerals, and a review of pet-food ingredients supports their nutritional value (de Godoy 2016). The idea that grains are inherently harmful comes from marketing, not veterinary evidence.

Can dogs digest grains and starch?

Yes. Dogs evolved to digest starch during domestication and carry, on average, a sevenfold increase in copies of the starch-digesting AMY2B gene compared with wolves (Axelsson 2013). Cooked grains are well within a dog's digestive ability.

Is grain-free dog food better for dogs?

No. There is no evidence that healthy dogs need grain-free food, and the FDA has investigated a possible link between some grain-free diets high in legumes and heart disease (FDA). Unless a veterinarian advises otherwise for a specific medical reason, grain-free is not the safer choice.

Are grains a common allergy for dogs?

No. Food allergies are uncommon, and the most frequently reported triggers are animal proteins: beef, dairy, and chicken, with wheat the one grain on the top list (Mueller 2016). Oats and barley are rarely reported as allergens.

What are the healthiest grains for dogs?

Whole grains like oats and barley rank among the best. Both are rich in the soluble fiber beta-glucan, which in dogs lowered total, LDL, and VLDL cholesterol in a feeding trial (Vasconcellos 2018). They also supply minerals and steady, slow-release energy.

Are grains just cheap filler in dog food?

No. Whole grains carry the bran and germ, which hold protein, fiber, vitamins, and minerals (de Godoy 2016). At Petaluma, organic oats and barley are chosen for their nutrition, not to lower cost.

References

1. Axelsson E, Ratnakumar A, Arendt ML, et al. The genomic signature of dog domestication reveals adaptation to a starch-rich diet. Nature. 2013;495:360-364. Nature.
2. de Godoy MRC, Kerr KR, Fahey GC. Compositional analysis of whole grains, processed grains, grain co-products, and other carbohydrate sources with applicability to pet animal nutrition. Foods. 2016;5(2):23. PMC.
3. Vasconcellos RS, et al. Oat beta-glucan as a dietary supplement for dogs. PLOS ONE. 2018;13(7):e0201133. PLOS ONE.
4. Tosh SM. Review of human studies investigating the post-prandial blood-glucose lowering ability of oat and barley food products. European Journal of Clinical Nutrition. 2013;67:310-317. EJCN.
5. Mueller RS, Olivry T, Prélaud P. Critically appraised topic on adverse food reactions of companion animals (2): common food allergen sources in dogs and cats. BMC Veterinary Research. 2016;12:9. PubMed.
6. U.S. Food and Drug Administration. FDA Investigation into Potential Link between Certain Diets and Canine Dilated Cardiomyopathy. FDA.